Exposure of animals and man during development can result in teratogenic, mutagenic, and carcinogenic outcomes. The proposed research will determine whether transgenic mouse models used for mutagenicity testing can be used to identify transplacental mutagens. Phase I will be a proof- of-principle study to demonstrate the applicability of the approach using a known mutagen. In Phase II, the assay will be further characterized using additional chemicals and different exposure protocols, as well as by determining whether or not the mutant spectra of the mutagen of interest is different in the same tissue of the mother and her offspring. This assay will be used to identify transplacental mutagens and will offer the opportunity of determining whether mutations which occur during development are related to teratogenic and carcinogenic outcomes. PROPOSED COMMERCIAL APPLICATION: The transplacental transgenic mutation assay will be used to detect chemicals capable of inducing mutations in developing organisms in utero. The technique will become a standard commercial assay for identifying potential transplacental mutagens.